Okay, to try and get back on topic, let me rephrase my question: Are there any post-1945 PODs that could have led to a dramatic degradation in civil rights, the rule of law, political pluralism, and the electoral process in the core western powers? (Meaning much worse than today.)
(Aside from May 58, of course.)
It's hard to say, but I will say that even in Western democracies like America, civil liberties were always shaky during that period.
In America, at least, you had McCarthyism, the FBI infiltrating civil rights organizations and the communism party, J. Edgar Hoover's psychotically antagonistic attitude to MLK, the violent reaction in Southern states to pro-civil rights legislation, the war on drugs, the Philadelphia police bombing a black neighborhood, CIA shenanigans, etc. I'd say there was always a chance for America to become more draconian, but I think the POD would have to be some race or protest movement going so badly that the government thinks it has to be draconian.
But there are a couple of TLs that depict an authoritarian America.
A World of Laughter, A World of Tears, depicts Walt Disney becoming President in 1953. Long story short, Disney's political naivete means he ends up damaging the civil rights movement to the degree that it creates a cycle of violence in which civil rights activists become more violent and the government more draconian until blacks are subjected to actual apartheid laws. A friggin' Nazi, George Lincoln Rockwell, becomes a senator from Virginia, and the racist John Stennis becomes President. It also features Orson Welles making a Batman movie, Goldwater and Nixon as heroes for civil liberties, Disney fans becoming Hitler Youth, and Bill Clinton being the head of the SLCP.
Fear Loathing and Gumbo and
Rumsfeldia depicts an America degenerating into hypercapitalist tyranny and later totalitarian theocracy because a governor from Louisiana ran for President in 1972, causing a constitutional crisis that led to Spiro Agnew becoming President, the economic problems of the 1970s becoming much worse, Mao's nephew dealing crack, and Donald Rumsfeld effectively being an anarcho-capitalist Pinochet.
In both cases, the racial, political, and economic problems of America become much worse, radicalizing OTL people into doing things they didn't do in our timeline and opening the door for bigger crazies to enter the halls of power.
So a TL where this happens has to feature an OTL event happening, but its consequences end up damaging America even more.